Grant Shapps, the Conservative Party chairman, has claimed he was only joking
when he used a fake name to promote his get-rich-quick business.

Mr Shapps is being investigated by the Advertising Standards Agency over his use of an alias, but he last night insisted his real identity was "never a secret"

The senior MP said he is "absolutely not embarrassed" about having built a successful business under the name of Michael Green while he was recovering for Hodgkin's Lymphoma, a type of cancer.

Hitting back at his critics, Mr Shapps said he only attended an event with a name badge reading "Michael Green" because it was his pseudonym used to write books like How to Get Stinking Rich.

"It was a conference joke," he told the Evening Standard. “Everyone knew who I was. It was not a secret, never was. Authors using pen names is normal. Nigel West is really Rupert Allason [ a former Tory MP and spy writer] and people didn’t care.”

Mr Shapps also denied accusations that he bought Twitter followers and said he only ever edited his Wikipedia entry to make it accurate.

He spoke out to defend himself after Ed Miliband, the Labour leader, mocked the Conservative chairman for his multiple identities.

“I’m absolutely not embarrassed about having done something that Ed Miliband has never done – which is to build up a business from scratch,” Mr Shapps told the newspaper.

“I know what it’s like to get up early and graft – and to put my house on the line to buy the next printing press, pray it works out, and pay my employees at the end of the week.

“It’s easy to make speeches saying ‘I know how difficult it is for working people’. But I have actually been a working person.

“Some of us did stuff before we went into politics. Miliband has no other experience at all. He’s the one who must think he was born to rule because he never went for any other job.”

The probe into Mr Shapps is focusing on his claims to be a self-help guru called Michael Green on a website called howtocorp.com.

A complaint to the ASA alleges that the website misled the public by presenting Michael Green as a genuine businessman with a personal fortune of £17 million, who would share the secrets of his success for a fee.

It relates to a website entitled “Sebastian Fox’s How To Corp – The Home of Great Toolkits on the Net”, which includes links to articles on each advertised “toolkit” which it says are written by Michael Green.